feat: add initial release with installation instructions, service configuration, and man page

INSTALL.md

@@ -0,0 +1,81 @@
+# Installation
+
+## AUR (Arch Linux)
+
+```bash
+yay -S k-shrink
+```
+
+AUR page: https://aur.archlinux.org/packages/k-shrink *(placeholder — submit PKGBUILD first)*
+
+Then enable the service:
+
+```bash
+systemctl --user enable --now k-shrink.service
+```
+
+---
+
+## Manual (from source)
+
+**Prerequisites:** Rust toolchain, `wayland` libraries.
+
+```bash
+git clone https://github.com/PLACEHOLDER/k-shrink
+cd k-shrink
+cargo build --release
+```
+
+Install the binary:
+
+```bash
+install -Dm755 target/release/k-shrink ~/.local/bin/k-shrink
+```
+
+Install the systemd service:
+
+```bash
+mkdir -p ~/.config/systemd/user
+cp contrib/k-shrink.service ~/.config/systemd/user/
+systemctl --user enable --now k-shrink.service
+```
+
+Install the man page (optional):
+
+```bash
+mkdir -p ~/.local/share/man/man1
+cp man/k-shrink.1 ~/.local/share/man/man1/
+gzip ~/.local/share/man/man1/k-shrink.1
+mandb ~/.local/share/man   # update man index
+```
+
+---
+
+## cargo install
+
+```bash
+cargo install --git https://github.com/PLACEHOLDER/k-shrink k-shrink
+```
+
+Then enable the service (uses `%h/.cargo/bin/k-shrink`):
+
+```bash
+mkdir -p ~/.config/systemd/user
+# Download the service file from the repo contrib/ directory, then:
+systemctl --user enable --now k-shrink.service
+```
+
+---
+
+## Verifying
+
+```bash
+systemctl --user status k-shrink.service
+# Copy an image, then paste — it should arrive compressed.
+```
+
+Logs:
+
+```bash
+journalctl --user -u k-shrink.service -f
+```